PURPOSE: To reduce the number of components and to enhance the degree of freedom of design considerably by utilizing an internal cell to form an oscillation circuit without adding an external connection terminal.

CONSTITUTION: The resistance of resistors 1, 6 is made variable by utilizing polysilicon being a component of an internal cell. Moreover, the capacitance of a capacitor 5 is made variable by utilizing a gate electrode capacitance of the internal cell and the accuracy several times higher than that of a conventional RC oscillator is realized. The oscillation circuit is built in in this way to attain the master slice system semiconductor integrated circuit without extending the number of connection terminals and the number of components is reduced and the cost is decreased in integrating the circuit system and the accuracy and resolution are far excellent more than those of an oscillation circuit comprising discrete resistors and capacitors.